Webster's Revised Unabridged Dictionary · 1913

Tome

Tome (tōm) , noun

[French tome (compare Italian, Sp., & Portuguese tomo), Latin tomus, from Greek {not transcribed} a piece cut off, a part of a book, a volume, akin to {not transcribed} to cup, and perhaps to Latin tondere to shear, English tonsure. Compare Anatomy, Atom, Entomology, Epitome. ]

As many writings as are bound in a volume, forming part of a larger work; a book; -- usually applied to a ponderous volume.
Tomes of fable and of dream. — Cowper
A more childish expedient than that to which he now resorted is not to be found in all the tomes of the casuists. — Macaulay